Proteins are necessary for tissue repair and for the construction of new tissue. Every cell needs protein to maintain its life. Protein is also the primary substance used to replace worn out or dead cells. Your muscles, hair, nails, skin, and eyes are made of protein.
Taking supplemental chromium has been shown repeatedly to improve insulin sensitivity and glucose tolerance, even to the point of reversing type II diabetes in many people (1). Thus, as my old clinical nutrition professor pointed out, apparently a chromium deficiency can actually lead to type II diabetes.
There are a few supplements which may worsen blood sugar control or insulin sensitivity in certain people: excessive amounts of niacin may elevate blood sugar levels, and prescription digestive enzymes may cause an increase or decrease in blood sugar levels in people with exocrine pancreatic insufficiency.